Perfusion Trend Indicator Using Segmented Waveform Analysis
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Solution Overview
Problem
Current pulse oximetry systems lack a mechanism to effectively alert clinicians to significant changes in perfusion index (PI) over time, which is crucial for monitoring patient conditions and detecting potential deteriorations.
Innovation Solution
A perfusion index trend indicator is introduced, which establishes a baseline PI and calculates trends by inputting plethysmograph waveforms, deriving perfusion values, and determining representative values within defined time windows, allowing for user-selectable alarms when a specified decrease in PI is detected, enabling audible and visual alerts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pulse oximetry systems provide only numerical readouts and basic waveforms, then the device complexity is low, but the ability to detect and alert clinicians to significant perfusion changes is insufficient
Solution Approach 1:
The patent segments the continuous plethysmograph waveform into discrete time windows (e.g., 30-second intervals) and calculates representative perfusion index values for each window. This segmentation allows the system to track perfusion trends over time without requiring complex continuous analysis, thereby improving detection capability while maintaining manageable system complexity
Solution Approach 2:
The system performs preliminary calculations by establishing a baseline perfusion index and pre-defining alarm thresholds before clinical use. By preparing these reference values in advance, the system can quickly compare current readings against established benchmarks and trigger alarms when significant deviations occur, enhancing reliability without adding real-time computational complexity
2Measurement precision
If the system continuously monitors and analyzes perfusion data in real-time, then the detection precision improves, but the loss of time for processing and displaying information increases
Solution Approach 1:
The patent implements periodic monitoring by calculating perfusion index values at regular intervals (e.g., every 30 seconds) and comparing them against the baseline at defined time points (ΔT). This periodic approach provides precise trend detection through systematic sampling while avoiding the continuous processing overhead, thus reducing time loss without sacrificing measurement precision
Solution Approach 2:
The system applies partial action by selectively triggering alarms only when perfusion changes exceed predetermined thresholds (ΔPI), rather than continuously alerting for every minor fluctuation. This approach maintains high detection precision for clinically significant changes while minimizing unnecessary processing and display updates, thereby reducing overall time loss
3Loss of information
If the system provides detailed perfusion analysis and trend tracking, then the information completeness improves, but the ease of operation decreases due to increased alarm management complexity
Solution Approach 1:
The patent applies local quality by providing different levels of information display: a simplified view showing only critical alarm conditions for ease of operation, and a detailed view displaying comprehensive perfusion trends and baseline comparisons for complete information. This localized information presentation allows clinicians to access full perfusion data when needed while maintaining simple operation during routine monitoring
Solution Approach 2:
The system implements feedback by providing visual confirmation of alarm conditions through trend graphs that display current perfusion values against the baseline. This feedback mechanism helps clinicians quickly understand the nature and significance of alarms without requiring complex interpretation, thereby maintaining ease of operation while delivering complete perfusion information
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides timely alerts to clinicians about important changes in perfusion index, enabling prompt intervention in patient care by displaying perfusion trend graphs and triggering alarms when predefined PI thresholds are breached, thus improving patient monitoring and treatment responsiveness.
Implementation Method 1
The sensor has light emitting diodes (LEDs) that transmit optical radiation of red and infrared wavelengths into a tissue site and a detector that responds to the intensity of the optical radiation after attenuation by pulsatile arterial blood flowing within the tissue site
Data Source
AI summary
A perfusion trend indicator inputs a plethysmograph waveform having pulses corresponding to pulsatile blood flow within a tissue site. Perfusion values are derived corresponding to the pulses. Time windows are defined corresponding to the perfusion values. Representative perfusion values are defined corresponding to the time windows. A perfusion trend is calculated according to differences between representative perfusion values of adjacent ones of the time windows.